Embodiments of the present invention generally relate to marine geophysical processing and may have particular applicability to electromagnetic surveying. More specifically, cable configurations are disclosed that may be used for geophysical prospecting.
In geophysical prospecting in a marine environment, cable configurations are often towed behind a vessel to generate electromagnetic (“EM”) signals that may be helpful in identifying geophysical features. Wires or cables for generating such signals may be bundled into source cables (also called “sources”) that are commonly jacketed or wrapped in an enclosure. The jacketing serves a number of purposes in the conventional EM source, including preventing exposure of some components to water and providing buoyancy. A cable assembly having proper buoyancy will maintain a desired depth as it is towed through the water.
FIG. 1 is a drawing of a prior art EM source cable assembly 1. The prior art cable assembly 1 is shown partially lying on, and partially wrapped around, a spool 4. The cable assembly 1 has a connector 2 at each end thereof for connecting to a vessel or to another cable. The body 3 of the cable assembly 1, lying on, and wrapped around, the spool 4 in loops, has a surface characteristic of the jacketing material commonly used for such cable assemblies.
As mentioned above, conventional EM source cable assemblies typically include wires, and sometimes devices, wrapped in a jacketing material. Buoyancy members may be bundled with the wires and devices, and the full assembly may be jacketed. Such cable assemblies can build up heat from power flowing through the wires, in some cases requiring additional features or specialized devices or materials to remove or manage heat. This may be especially problematic for operations using high-power sources. Additionally, replacing wires and devices often requires disassembling the cable assembly, replacing malfunctioning wires and devices, and reassembling the cable assembly. Thus, there is a need for new cable assemblies that can be used for geophysical prospecting.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.